Mehanske lastnosti in kinetika zamreževanja aromatskih epoksidov z aminomaleimidom

Kovačič, Žan (avtor), Ručigaj, Aleš (mentor)

V prvem koraku raziskovalnega dela sem izvedel sintezo aminomaleimida, ki je bila ključna komponenta pri zamreževanju z različnimi epoksi smolami. Z namenom preučevanja vpliva dodatka aminomaleimida na termo-mehanske lastnosti in kinetiko zamreževanja sem pripravil mešanice aminomaleimida in epoksi smol v treh razmerjih. Raziskovanje sem razširil z izborom aromatskih in alifatskih epoksi smol različnih molskih mas, struktur in števila funkcionalnih epoksi skupin ter njihove razvejanosti. Za primerjalno osnovo sem epoksi smole zamreževal še z diaminskim in dimaleimidnim zamreževalom, kjer sem prav tako preučeval kinetiko zamreževanja in termo-mehanske lastnosti. Ugotovil sem, da prisotnost maleimidne skupine ne sproži procesa zamreževanja, niti pri povišani temperaturi, medtem ko aminska skupina pričakovano sledi v literaturi že dobro razloženim fenomenom zamreževanja epoksi smol. Termične lastnosti zamreževanja epoksi smol sem določil prek diferenčne dinamične kalorimetrije (DSC), ki je bila tudi osnova za kasnejšo analizo kinetike zamreževanja. Reakcija zamreževanja epoksi smol z aminomaleimidom sledi avtokatalitičnemu režimu, kar sem opisal v obliki Šesták-Berggrenovega modela. Avtokatalitičnost sem potrdil teoretično z Malékovo analizo in metodo po Friedmanu. Kinetične parametre sem določil s prileganjem kinetičnega modela k eksperimentalnim podatkom preko metode najmanjših kvadratov in dosegel zadovoljivo ujemanje. Mehanske lastnosti zamreženih vzorcev sem določil z metodo dinamične mehanske analize (DMA). Rezultati DMA analiz so potrdili, da dodatek maleimidne skupine izboljša mehanske lastnosti materiala. Opazen je bil tudi trend naraščanja temperature steklastega prehoda relativno na dodatek maleimidne skupine. Večji kot je bil dodatek aminomaleimida v zamreženem vzorcu, višja temperatura steklastega prehoda je bila dosežena. Hkrati se je izkazalo, da tudi aromatske skupine v epoksi smoli vplivajo na pomik temperature steklastega prehoda k višji temperaturi v primerjavi z alifatskimi primerki. Ugotovil sem, da z uporabo aminomaleimida dosežemo boljše termo-mehanske lastnosti kot v primeru referenčnega diamina 4,4-diamino difenil metan. Termogravimetrična analiza je presenetljivo pokazala boljšo termično obstojnost referenc kot aminomaleimida, je pa trden ostanek višji z višanjem deleža aminomaleimida. Kljub vsemu bi bilo za absolutne vrednosti meritev potrebno meritve nadgraditi z meritvami v molskih razmerjih 1:1, s čimer bi lahko enoznačno ugotovili, katera mešanica predstavlja najboljše termo-mehanske lastnosti, in ali na to vpliva tudi molska masa.

• Jezik: Slovenski jezik
• Ključne besede: Aminomaleimid, Epoksi smole, Kinetični model, Termo-mehanske lastnosti.
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2019
• PID: 20.500.12556/RUL-110519
• COBISS.SI-ID: 1538432195
• Datum objave v RUL: 16.09.2019

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Mechanical properties and curing kinetics of aromatic epoxides with aminomaleimide

Izvleček

The first part of the research consisted of synthesis of aminomaleimide which was a key ingredient in cross-linking with various epoxy resins. Furthermore, to investigate the effect of maleimide group on thermomechanical properties of the material, three mixtures of aminomaleimide and respective epoxy were produced. The research was further expanded by closely examining not only aromatic but also aliphatic epoxy resins of different molar masses, structures and functionality. As a reference epoxy resins were also cross-linked with diamine and dimaleimide compound, where the kinetics of reaction and their respective thermomechanical properties were studied. While the dimaleimide molecule did not react with epoxy resin, not even at elevated temperatures, the diamine reacted, which agrees with extensive literature on cross-linking phenomena between different epoxy and amine molecules. Thermal properties of the reaction were studied with differential scanning calorimetry (DSC), which provided data needed for further kinetic analysis. Reaction between aminomaleimide and epoxy was determined to follow the autocatalytic model, additionally proven as Šesták-Berggren model. The autocatalytic nature of the reaction was theoretically verified using Malék analysis and by Friedman method. Kinetic parameters were determined by approximating the theoretical model to experimental data using least square difference method achieving satisfactory agreement. The mechanical properties of cross-linked materials were observed with dynamical mechanical analysis (DMA). The results confirmed that the addition of maleimide group improves mechanical properties. Increase of the glass transition temperature, relatively to the amount of maleimide added, was observed. The higher the amount of maleimide group, the higher the glass transition temperature. Meanwhile, aromatic epoxides exhibit shifts of glass transition temperature to higher values, compared to their aliphatic competitors. It was also determined that cross-linking with aminomaleimide, compared to the reference 4,4-diaminodiphenylmethane, improves thermomechanical properties. TGA surprisingly demonstrated higher temperatures of decomposition of reference mixtures, however char yield did improve relatively to the addition of aminomaleimide. Despite the above, to get absolute values on improvement of materials, a molar mixture 1:1 of all samples should be measured as to determine which mixture provides the best thermomechanical properties and if molar mass and structure of epoxides plays a significant role.

• Ključne besede: Aminomaleimide, Epoxy, Kinetics, Thermomechanical properties.